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/* $OpenBSD: gcvt.c,v 1.13 2013/11/01 19:05:11 guenther Exp $ */ |
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/* |
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* Copyright (c) 2002, 2003, 2006, 2010 |
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* Todd C. Miller <Todd.Miller@courtesan.com> |
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* |
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* Permission to use, copy, modify, and distribute this software for any |
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* purpose with or without fee is hereby granted, provided that the above |
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* copyright notice and this permission notice appear in all copies. |
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* |
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES |
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF |
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR |
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES |
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN |
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF |
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. |
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* |
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* Sponsored in part by the Defense Advanced Research Projects |
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* Agency (DARPA) and Air Force Research Laboratory, Air Force |
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* Materiel Command, USAF, under agreement number F39502-99-1-0512. |
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*/ |
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#include <locale.h> |
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#include <stdio.h> |
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#include <stdlib.h> |
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#include <string.h> |
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#include "gdtoa.h" |
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#define DEFPREC 6 |
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char * |
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gcvt(double value, int ndigit, char *buf) |
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{ |
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char *digits, *dst, *src; |
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int i, decpt, sign; |
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struct lconv *lconv; |
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lconv = localeconv(); |
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if (ndigit <= 0) { |
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/* Match printf(3) behavior. */ |
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ndigit = ndigit ? DEFPREC : 1; |
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} |
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digits = __dtoa(value, 2, ndigit, &decpt, &sign, NULL); |
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if (digits == NULL) |
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return (NULL); |
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if (decpt == 9999) { |
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/* |
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* Infinity or NaN, convert to inf or nan with sign. |
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* We can't infer buffer size based on ndigit. |
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* We have to assume it is at least 5 chars. |
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*/ |
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snprintf(buf, 5, "%s%s", sign ? "-" : "", |
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*digits == 'I' ? "inf" : "nan"); |
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__freedtoa(digits); |
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return (buf); |
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} |
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dst = buf; |
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if (sign) |
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*dst++ = '-'; |
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/* Match printf(3) behavior for exponential vs. regular fomatting. */ |
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if (decpt <= -4 || decpt > ndigit) { |
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/* exponential format (e.g. 1.2345e+13) */ |
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if (--decpt < 0) { |
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sign = 1; |
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decpt = -decpt; |
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} else |
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sign = 0; |
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src = digits; |
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*dst++ = *src++; |
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if (*src != '\0') { |
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*dst++ = *lconv->decimal_point; |
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do { |
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*dst++ = *src++; |
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} while (*src != '\0'); |
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} |
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*dst++ = 'e'; |
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if (sign) |
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*dst++ = '-'; |
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else |
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*dst++ = '+'; |
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if (decpt < 10) { |
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*dst++ = '0'; |
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*dst++ = '0' + decpt; |
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*dst = '\0'; |
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} else { |
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/* XXX - optimize */ |
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for (sign = decpt, i = 0; (sign /= 10) != 0; i++) |
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continue; |
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dst[i + 1] = '\0'; |
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while (decpt != 0) { |
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dst[i--] = '0' + decpt % 10; |
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decpt /= 10; |
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} |
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} |
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} else { |
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/* standard format */ |
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for (i = 0, src = digits; i < decpt; i++) { |
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if (*src != '\0') |
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*dst++ = *src++; |
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else |
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*dst++ = '0'; |
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} |
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if (*src != '\0') { |
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if (src == digits) |
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*dst++ = '0'; /* zero before decimal point */ |
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*dst++ = *lconv->decimal_point; |
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while (decpt < 0) { |
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*dst++ = '0'; |
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decpt++; |
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} |
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for (i = decpt; digits[i] != '\0'; i++) { |
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*dst++ = digits[i]; |
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} |
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} |
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*dst = '\0'; |
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} |
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__freedtoa(digits); |
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return (buf); |
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} |